With advances in communication technology, more and more communication function could be implemented and integrated into a single portable communication device. The current systems which could be integrated into the portable communication device include Wireless Wide Area Network (WWAN) System, Long Term Evolution (LTE) System, Wireless Personal Network (WLPN) System, Wireless Local Area Network (WLAN) System, Near Field Communication (NFC) System, Digital Television Broadcasting System (DTV), Global Positioning System (GPS), and other wireless applications.
The rising demand for signal quality, reliability and transmission rate of wireless communication system causes rapid development in multi-antenna systems technology. For example, Multi-Input Multi-Output (MIMO) Antenna System, Pattern Switchable Antenna System, Beam-Steering/Beam-Forming Antenna System, etc. However, in a multi-antenna system, the envelope correlation coefficient (ECC) between multiple antennas increases when the multiple antennas operating in the same frequency band are jointly designed in a handheld communication device with limited available antenna space. Increasing envelope correlation coefficient (ECC) causes attenuation of the antenna radiation characteristics, this thereby causes decreased data transmission rate and increased technical difficulties and challenges with the multi-antenna integrated design.
Part of the literature in the prior art proposes a design approach that involves designing protruding or slit structures on the ground area between multiple antennas to serve as an energy isolator, so as to enhance energy isolation between multiple antennas. However the above design approach would lead to the triggering of additional coupling current on the ground area and thereby increases the envelope correlation coefficient (ECC) between multiple antennas.
In order to address the above issue, the present disclosure provides a multiple antenna array design approach with a low envelope correlation coefficient (ECC) to satisfy the practical demands of a future high data transmission rate multi-antenna system.